test: extract shared test helpers into @local/testkit

[Rel1cx]

• Add .pkgs/testkit (@local/testkit, source-only internal package) with parseCode/collectNodes/getFirstNodeOfType, runInRule/getNodeInRule/ runCollector, createScopeContext, and createRuleTesterForJsxEmit
• Turn testing/helpers into re-export shims for backward compatibility
• Migrate 24 package unit tests and 2 rule specs to the shared kit, removing per-file copy-pasted harness boilerplate
• Document the new helpers in docs/rule-implementation-patterns.md and docs/repo-path-aliases.md

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Project	Deployment	Actions	Updated (UTC)
eslint-react	Ready	Preview, Comment	Jul 18, 2026 5:17pm

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Pull request overview

Adds a shared internal test helper package (@local/testkit) and migrates existing unit/rule tests to use it, keeping #/testing/helpers as backward-compatible re-export shims.

Changes:

• Introduces .pkgs/testkit with shared parsing, linter harness, RuleTester setup, and scope-context helpers.
• Replaces testing/helpers/* implementations with re-exports from @local/testkit.
• Updates multiple package/plugin tests and docs to use the shared helpers; wires workspace deps accordingly.

Reviewed changes

Copilot reviewed 45 out of 46 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
testing/helpers/rule-tester.ts	Re-export RuleTester helpers from @local/testkit.
testing/helpers/lint-runner.ts	Re-export ESLint runner helper from @local/testkit.
testing/helpers/get-fixtures-root-dir.ts	Re-export fixtures root resolver from @local/testkit.
plugins/eslint-plugin-react-jsx/src/rules/no-key-after-spread/no-key-after-spread.spec.ts	Uses createRuleTesterForJsxEmit instead of bespoke RuleTester setup.
plugins/eslint-plugin-react-debug/src/rules/jsx/jsx.spec.ts	Uses createRuleTesterForJsxEmit instead of bespoke RuleTester setup.
packages/var/src/resolve.test.ts	Migrates custom linter harness to runInRule.
packages/var/src/resolve-import-source.test.ts	Migrates parsing/fixtures to parseCode + getFixturesRootDir.
packages/var/src/resolve-enclosing-assignment-target.test.ts	Migrates parsing to parseCode.
packages/var/src/is-value-equal.test.ts	Migrates custom linter harness to runInRule.
packages/var/src/is-assignment-target-equal.test.ts	Migrates custom linter harness to runInRule.
packages/var/src/compute-object-type.test.ts	Migrates custom linter harness to runInRule.
packages/var/package.json	Adds @local/testkit devDependency.
packages/jsx/src/text.test.ts	Migrates JSX node capture to getNodeInRule.
packages/jsx/src/element.test.ts	Migrates JSX node capture to getNodeInRule.
packages/jsx/src/children.test.ts	Migrates JSX node capture to getNodeInRule.
packages/jsx/src/attribute-value.test.ts	Migrates context+node capture to getNodeInRule.
packages/jsx/src/attribute-find.test.ts	Migrates context+node capture to getNodeInRule.
packages/jsx/package.json	Adds @local/testkit devDependency.
packages/core/src/jsx.test.ts	Migrates parsing/scope-context construction to parseCode + createScopeContext.
packages/core/src/hook.test.ts	Migrates parsing to parseCode.
packages/core/src/hook-collector.test.ts	Migrates collector harness to runCollector.
packages/core/src/function.test.ts	Migrates parsing to parseCode.
packages/core/src/function-component.test.ts	Migrates parsing to parseCode.
packages/core/src/function-component-collector.test.ts	Migrates collector harness to runCollector.
packages/core/src/class.test.ts	Migrates parsing to parseCode.
packages/core/src/class-component.test.ts	Migrates parsing to parseCode.
packages/core/package.json	Adds @local/testkit devDependency.
packages/ast/src/traverse.test.ts	Migrates parsing to parseCode.
packages/ast/src/extract.test.ts	Migrates node extraction to getFirstNodeOfType.
packages/ast/src/compare.test.ts	Migrates node collection to collectNodes.
packages/ast/src/check.test.ts	Migrates helpers to @local/testkit (fixtures + node extraction).
packages/ast/package.json	Adds @local/testkit devDependency.
docs/rule-implementation-patterns.md	Documents new shared helpers and preferred usage patterns.
docs/repo-path-aliases.md	Documents @local/testkit vs #/testing/helpers guidance.
.pkgs/testkit/package.json	Declares new internal @local/testkit package and exports.
.pkgs/testkit/tsconfig.json	TypeScript config for the new package.
.pkgs/testkit/tsl.config.ts	TSL config for the new package.
.pkgs/testkit/src/index.ts	Barrel exports for testkit helpers.
.pkgs/testkit/src/fixtures.ts	Implements fixtures root resolution for testkit.
.pkgs/testkit/src/parse.ts	Adds parseCode + node collection helpers.
.pkgs/testkit/src/linter.ts	Adds runInRule, getNodeInRule, runCollector harnesses.
.pkgs/testkit/src/mock-context.ts	Adds createScopeContext helper for scope-aware contexts.
.pkgs/testkit/src/rule-tester.ts	Centralizes RuleTester + vitest wiring and JSX-emit helpers.
.pkgs/testkit/src/lint-runner.ts	Adds lintWithConfig helper implementation.
package.json	Adds workspace dependency on @local/testkit.
pnpm-lock.yaml	Locks new workspace package and dependency graph updates.

Files not reviewed (1)

• pnpm-lock.yaml: Generated file

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Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	lucide-react@​1.25.0
	tailwindcss@​4.3.3
	vite@​8.1.5
	eslint-plugin-jsdoc@​63.0.14
	tsdown@​0.22.9
	@​tailwindcss/​postcss@​4.3.3

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